Time resolved circular dichroism spectroscopy is a technique that we have developed in our laboratory for the study of protein conformational dynamics. The capabilities of our experimental approach allows one to measure conformational motions of proteins that occur on the picosecond or slower time scale. In this proposal, we discuss, in detail, the experimental approach for measuring time resolved circular dichroism spectra on the picosecond time scale and applications of our technique to the study of protein conformation changes caused by the photoinduced debinding of substrates bound to myoglobin, hemoglobin and model systems. In addition, we discuss future applications of our new experimental technique to determine (1) protein motions induced by the isomerization of retinal in the visual protein rhodopsin, and (2) changes in protein structure caused by electron transfer chemistry in hybrid hemoglobins.